Treasury Bills have a maturity of less than 12 months, have no coupon rate, and are issued at a discount to the par value. When a U.S. Treasury Bill matures it pays the par value only and pays no additional coupon interest. The returns the investor earns for a T-Bill is the difference between the purchase price and the maturity price.
Treasury Notes have a maturity of one to ten years, while Treasury Bonds have a maturity longer than ten years. Treasury Notes and Bonds both have a set coupon rate when they are issued, and will pay interest at the coupon rate and return the capital when they mature.